I have 3 Silkie mix pullets. I also have Bluebird boxes in my yard. The past few days the baby Bluebirds have been fledging & so everytime I went to the chicken run, the male Bluebird would give his warning call. All 3 chickens would then wildly dash under their Eglu Up as if the sky was falling. This has happened 3 times. Are they recognizing the warning call of the Bluebird?